WEBVTT - What is a quantum eraser? 0:00:01.280 --> 0:00:03.440 Hey, Jorhan, Daniel here, and we want to tell you 0:00:03.480 --> 0:00:07.280 about our new book. It's called Frequently Asked Questions about 0:00:07.320 --> 0:00:09.880 the Universe because you have questions about the universe, and 0:00:09.960 --> 0:00:12.360 so we decided to write a book all about them. 0:00:12.440 --> 0:00:14.800 We talk about your questions, we give some answers, we 0:00:14.880 --> 0:00:17.520 make a bunch of silly jokes as usual, and we 0:00:17.600 --> 0:00:20.159 tackle all kinds of questions, including what happens if I 0:00:20.200 --> 0:00:22.880 fall into a black hole? Or is there another version 0:00:22.920 --> 0:00:25.480 of you out there that's right? Like usual, we tackle 0:00:25.600 --> 0:00:29.960 the deepest, darkest, biggest, craziest questions about this incredible cosmos. 0:00:29.960 --> 0:00:31.800 If you want to support the podcast, please get the 0:00:31.800 --> 0:00:33.879 book and get a copy, not just for yourself, but 0:00:34.120 --> 0:00:39.360 you know, for your nieces and nephews, cousins, friends, parents, dogs, hamsters, 0:00:39.400 --> 0:00:42.640 and for the aliens. So get your copy of Frequently 0:00:42.720 --> 0:00:46.440 Asked Questions about the Universe is available for pre order now, 0:00:46.520 --> 0:00:49.239 coming out November two. You can find more details at 0:00:49.240 --> 0:00:53.160 the book's website, Universe f a Q dot com. Thanks 0:00:53.159 --> 0:00:55.000 for your support, and if you have a hamster that 0:00:55.040 --> 0:00:57.240 can read, please let us know. We'd love to have 0:00:57.320 --> 0:01:08.720 them on the podcast. Daniel, do you ever feel like 0:01:08.760 --> 0:01:11.880 you really understand quantum mechanics. No, you know, I think 0:01:11.880 --> 0:01:14.680 it's probably just too alien for us to really ever 0:01:14.760 --> 0:01:17.320 feel comfortable with. I guess it's too bad there aren't 0:01:17.319 --> 0:01:20.920 any macroscopic big quantum optics we can really like poke 0:01:21.000 --> 0:01:23.280 and play with, I know, like a big fat electron. 0:01:23.680 --> 0:01:26.640 But actually I'm working on a theory that children are 0:01:26.720 --> 0:01:29.440 governed by the rules of quantum mechanics. Oh really, like 0:01:29.480 --> 0:01:33.640 there's uncertainty about where they are. Have you lost your kids? No, 0:01:33.840 --> 0:01:36.360 but I've noticed that you can't like observe your children 0:01:36.400 --> 0:01:39.440 without sort of perturbing the system, right, I think I 0:01:39.440 --> 0:01:41.080 know what you mean. Like they won't do their homework 0:01:41.160 --> 0:01:44.399 unless you're there watching exactly. And when I walk into 0:01:44.400 --> 0:01:48.200 the room somehow all their conversations collapse suddenly into silence. Yeah, 0:01:48.240 --> 0:01:51.000 it's like sure the anger as children, they're both excited 0:01:51.080 --> 0:02:08.480 and sad to see you. Hi am for Handmad cartoonists 0:02:08.480 --> 0:02:11.160 and the creator of PhD comics. Hi. I'm Daniel. I'm 0:02:11.200 --> 0:02:14.239 a particle physicist and a professor UC Irvine, and I'm 0:02:14.280 --> 0:02:17.560 always in many quantum states at once. Really, so that 0:02:17.639 --> 0:02:20.519 does that mean you're not real? It means I don't 0:02:20.520 --> 0:02:23.080 even know if I'm real man. Well, I hope you are, 0:02:23.200 --> 0:02:25.440 because that would mean that I'm talking to myself right now, 0:02:25.919 --> 0:02:28.400 and that would be a little concerning. Maybe you are 0:02:28.440 --> 0:02:30.600 the only brain in the universe and the rest of 0:02:30.600 --> 0:02:32.720 the universe is just part of your mind. That would 0:02:32.800 --> 0:02:35.680 make a lot of sense why I'm so successful and 0:02:35.720 --> 0:02:38.320 good looking. But anyways, welcome to our podcast. Daniel and 0:02:38.400 --> 0:02:41.280 Jorge explain the university production of I Heart Radio, in 0:02:41.320 --> 0:02:44.320 which we do try to explode our minds out to 0:02:44.600 --> 0:02:49.880 capture the entire universe. We want to take this vast, glittering, crazy, violent, 0:02:49.919 --> 0:02:53.079 wild and white cosmos and wrap it all up inside 0:02:53.080 --> 0:02:55.440 our brains. It's not enough for us to just live 0:02:55.480 --> 0:02:57.800 in this universe to experience it and to see it. 0:02:58.080 --> 0:03:01.160 We want to understand it. We want download the whole 0:03:01.200 --> 0:03:04.960 thing into our minds, and that means understanding the basic 0:03:05.160 --> 0:03:08.720 rules about how it works, what's really going on with 0:03:08.840 --> 0:03:12.960 tiny little particles or whatever is happening at the smallest scale. 0:03:13.240 --> 0:03:16.240 On this podcast, we dive the deepest you can into 0:03:16.240 --> 0:03:19.079 the hardest and trickiest of questions and we try to 0:03:19.160 --> 0:03:21.679 explain all of them to you. Yeah, because it is 0:03:21.720 --> 0:03:24.760 a pretty tricky universe. It's full of interesting rules and 0:03:24.840 --> 0:03:27.760 interesting phenomena that happens at the smallest of levels and 0:03:27.840 --> 0:03:30.280 at the largest of scales, and a lot of it 0:03:30.400 --> 0:03:34.360 is understandable, even if it's not very um intuitive to 0:03:34.400 --> 0:03:36.440 think about. That's right. And I look at the universe 0:03:36.520 --> 0:03:39.200 like a big puzzle. It's like a detective novel or 0:03:39.200 --> 0:03:41.720 a murder mystery, and I want to figure out who 0:03:41.760 --> 0:03:44.520 did it. I want to understand how it works. It's 0:03:44.520 --> 0:03:47.080 amazing to me, sort of philosophically, that the universe is 0:03:47.120 --> 0:03:49.240 presented to us that way, like this big puzzle that 0:03:49.360 --> 0:03:52.200 isn't obvious to figure out, but yet can somehow be 0:03:52.400 --> 0:03:54.280 understood if you push hard enough. Do you think the 0:03:54.360 --> 0:03:57.240 universe is understandable? Daniel? That's a big question in physics, 0:03:57.320 --> 0:03:59.680 isn't it. It's a big question in the philosophy of 0:03:59.680 --> 0:04:02.680 physics x and And my answer is it doesn't make 0:04:02.760 --> 0:04:05.560 sense for it to be understandable, Like how could it 0:04:05.600 --> 0:04:09.520 be possible that the complexities of this maybe infinite universe 0:04:09.640 --> 0:04:11.800 could be stored in the minds of a human. On 0:04:11.840 --> 0:04:13.600 the other hand, we have all these theories that work 0:04:13.800 --> 0:04:17.200 really well, like surprisingly well, and so I don't know 0:04:17.200 --> 0:04:19.120 how to hold those two ideas. In my mind, they're 0:04:19.120 --> 0:04:23.160 in quantum conflict. You're both confused and feeling smart at 0:04:23.200 --> 0:04:25.359 the same time. That's what this podcast is all about. 0:04:25.440 --> 0:04:28.360 I'm the confused quantum state and you are the feeling smart. 0:04:28.520 --> 0:04:30.960 That's right. And all scientists sort of hold those two 0:04:30.960 --> 0:04:33.039 feelings in their mind at once, like, look at all 0:04:33.120 --> 0:04:35.919 we have understood, and yet look at all that we 0:04:36.040 --> 0:04:39.640 do not, And that's both exciting and terrifying. Yeah, and 0:04:39.680 --> 0:04:42.160 we have a lot of questions about the universe. And 0:04:42.240 --> 0:04:44.839 by the way, speaking of questions, we have a new 0:04:44.839 --> 0:04:48.120 book coming out pretty soon in on November two. That's right. 0:04:48.200 --> 0:04:51.240 Jorge and I celebrate asking questions about the universe, and 0:04:51.279 --> 0:04:54.240 we love thinking about these questions. We love hearing about 0:04:54.279 --> 0:04:56.960 your questions about the universe. So we wrote a book 0:04:56.960 --> 0:05:00.320 that wraps up the most frequently asked questions that we 0:05:00.400 --> 0:05:02.880 get about the universe. Yeah. So, if you like this 0:05:02.920 --> 0:05:05.240 podcast and you want to support us, please check it out. 0:05:05.240 --> 0:05:08.440 It's called Frequently Ask Questions about the Universe and it's 0:05:08.480 --> 0:05:10.159 on a pre order right now. You can order it 0:05:10.200 --> 0:05:11.880 now and get it as soon as it comes out. 0:05:12.120 --> 0:05:14.200 And I think you know what's important is that we 0:05:14.320 --> 0:05:17.040 kind of didn't quite write it for our listeners, right, Daniel. 0:05:17.120 --> 0:05:19.400 We kind of wrote it for the people that know 0:05:19.480 --> 0:05:21.559 our listeners. You know, if you ever have like a 0:05:21.600 --> 0:05:23.680 nephew or a cousin or an uncle who you want 0:05:23.680 --> 0:05:26.120 to share this amazing information about the universe, I think 0:05:26.160 --> 0:05:28.600 this is the book for you or for them, that's right. 0:05:28.880 --> 0:05:30.440 So every one of you out there, you should buy 0:05:30.440 --> 0:05:32.760 five copies and give them to all your friends and 0:05:32.839 --> 0:05:35.800 family so that they can understand the answers to questions 0:05:35.839 --> 0:05:39.159 like where did the universe come from? Or how can 0:05:39.200 --> 0:05:41.880 we travel to the stars. Yeah, we tackle all kinds 0:05:41.920 --> 0:05:43.719 of pretty cool questions in it, and we try to 0:05:43.760 --> 0:05:47.400 answer it for people like your relatives and friends with 0:05:47.440 --> 0:05:50.880 all kinds of interesting and clear answers. And also cartoons, 0:05:50.920 --> 0:05:53.000 which is I think something you don't see in every 0:05:53.040 --> 0:05:55.840 day in physics books. That's right. All these awesome fun 0:05:55.920 --> 0:05:59.080 drawings that help clarify the topic and amuse you along 0:05:59.080 --> 0:06:01.960 the way. That or added to this book. So if 0:06:02.000 --> 0:06:05.240 you like this blend of physics and silly jokes, then 0:06:05.320 --> 0:06:07.400 I think you'll enjoy this book. So go out and 0:06:07.440 --> 0:06:09.960 get your copy. You can find it at universe f 0:06:10.120 --> 0:06:13.359 a Q dot com all right, Well, speaking of questions, 0:06:13.480 --> 0:06:15.719 we are tackling a question today and it has something 0:06:15.760 --> 0:06:19.200 to do with quantum mechanics, which is, I guess, for 0:06:19.360 --> 0:06:23.960 lack of a better technical term, bonkers. It is my 0:06:24.120 --> 0:06:27.320 favorite kind of bonkers. It's the kind of bonkers that 0:06:27.440 --> 0:06:30.800 doesn't make sense to your mind. But the math works 0:06:30.800 --> 0:06:36.280 perfectly and it keeps predicting absurd experimental conclusions that experimentalists 0:06:36.400 --> 0:06:39.080 keep verifying. Yeah, because I guess you started with a 0:06:39.080 --> 0:06:41.480 little nugget of an experiment, and then you worked out 0:06:41.520 --> 0:06:44.200 some math, and then you find out that the crazy 0:06:44.240 --> 0:06:46.919 math that it suggests is actually also true. Yeah, we 0:06:46.960 --> 0:06:49.839 had to change the basic concept of what we thought 0:06:49.920 --> 0:06:52.400 was going on at the very heart of the universe, 0:06:52.640 --> 0:06:54.960 at the core of everything that's around me and you. 0:06:55.000 --> 0:06:58.040 Even though it seems intuitive and like it follows rules 0:06:58.040 --> 0:07:00.200 that we're familiar with from growing up, it turn turns 0:07:00.200 --> 0:07:02.920 out that the tiniest little parts inside are following totally 0:07:02.960 --> 0:07:05.919 different rules, which mean that the nature of reality is 0:07:06.040 --> 0:07:08.479 quite different from the one that we thought it was. 0:07:09.040 --> 0:07:11.760 And people work that out and they thought that's crazy. 0:07:11.920 --> 0:07:14.120 And if it's true, it would mean you could do 0:07:14.200 --> 0:07:17.880 this bonkers experiment, which would have this nonsense result, so 0:07:18.040 --> 0:07:20.680 obviously it can't be true. And then business went out 0:07:20.680 --> 0:07:23.520 and did the experiment and got the nonsense results, which 0:07:23.520 --> 0:07:26.120 turns out to be the truth of our reality. Yeah, 0:07:26.160 --> 0:07:27.640 because I guess at the core of it, it's kind 0:07:27.680 --> 0:07:29.840 of weird for us humans to think of things that 0:07:29.920 --> 0:07:32.280 are like two things at the same time, right, I mean, 0:07:32.320 --> 0:07:35.080 not just in a conceptual ot but like actually in reality, 0:07:35.280 --> 0:07:38.360 in quantum objects, things can be multiple things at the 0:07:38.400 --> 0:07:41.280 same time. That's right, And that phrase in reality is 0:07:41.320 --> 0:07:44.000 the key there, because we imagine at the very basic 0:07:44.080 --> 0:07:47.280 level that there is a reality out there, that there's 0:07:47.320 --> 0:07:50.120 a truth that even if we're not looking, the universe 0:07:50.320 --> 0:07:53.320 is there and it's operating and it's following some rules 0:07:53.360 --> 0:07:55.960 and it doesn't really matter if we are looking or not. 0:07:56.640 --> 0:07:59.800 But the reality suggests that the universe is quite different 0:07:59.800 --> 0:08:02.920 from that, that it does matter if you interact with it, 0:08:03.120 --> 0:08:05.720 and that what is happening in the universe is not 0:08:05.840 --> 0:08:09.440 exactly well determined until you interact with it. Yeah, you 0:08:09.480 --> 0:08:11.960 might say that in reality, the way the world works 0:08:11.960 --> 0:08:14.320 and the universe works, it's kind of fuzzy, kind of 0:08:14.360 --> 0:08:16.880 not quite as solid as we might think it is. 0:08:16.920 --> 0:08:19.320 From our everyday lives. That's right. We have a weird 0:08:19.480 --> 0:08:22.600 and particular view of this quantum universe. We are only 0:08:22.720 --> 0:08:26.640 used to interacting with enormous quantum objects like baseballs and 0:08:26.760 --> 0:08:29.880 rocks and trees, which are quantum objects. But they contain 0:08:29.960 --> 0:08:33.080 like ten to the twenty six quantum objects. And when 0:08:33.080 --> 0:08:35.880 you have that many, they do things differently than when 0:08:35.880 --> 0:08:38.160 you have one or two of them isolated to reveal 0:08:38.240 --> 0:08:41.840 their sort of true fundamental nature. So today we're gonna 0:08:41.840 --> 0:08:44.920 be talking about some really crazy experiments that try to 0:08:44.960 --> 0:08:47.960 reveal exactly what the rules are of how these particles 0:08:48.000 --> 0:08:50.880 work at the smallest scale when they're left alone. Yeah, 0:08:50.960 --> 0:08:53.520 and so it turns out that also reality is not 0:08:53.600 --> 0:08:56.040 just a little bit fuzzy, but it may not even 0:08:56.120 --> 0:08:59.679 be as permanent as we think it is. Quantum in 0:08:59.760 --> 0:09:03.480 for meation and quantum things. We think they're there for real, 0:09:03.640 --> 0:09:06.400 but it turns out that maybe things can be taken 0:09:06.440 --> 0:09:09.200 away from the universe. That's right. This fuzzy question of 0:09:09.360 --> 0:09:11.880 what things are doing when you're not looking at them, 0:09:11.920 --> 0:09:13.760 and if you look at them and then look away, 0:09:14.200 --> 0:09:16.640 and it doesn't matter who's looking at them and how 0:09:16.679 --> 0:09:19.199 they look at them, and whether they store the information 0:09:19.200 --> 0:09:22.000 and look at it later. All these fun thought experiments 0:09:22.000 --> 0:09:24.559 can help us try to understand what's really going on 0:09:24.800 --> 0:09:27.240 at the smallest scales. So to be on the podcast, 0:09:27.280 --> 0:09:36.760 we'll be talking about what is a quantum eraser? Now, Daniel, 0:09:36.840 --> 0:09:39.240 is this a rubber eraser or what is it made 0:09:39.240 --> 0:09:41.520 out of? It's something which will erase your mind if 0:09:41.559 --> 0:09:44.000 you think about it too much. It's kind of stretch 0:09:44.040 --> 0:09:46.760 it out like a piece of rubber exactly, and push 0:09:46.760 --> 0:09:49.640 it too hard and it might just snap. No. Quantum 0:09:49.720 --> 0:09:53.200 eraser refers to the concept of quantum information and what 0:09:53.320 --> 0:09:57.080 happens if you create information and then erase that information 0:09:57.240 --> 0:09:59.760 from the universe. So it's an extension of some really 0:10:00.000 --> 0:10:02.640 on experiments that listeners on this podcast have heard us 0:10:02.640 --> 0:10:06.079 talk about, the double slit experiment, which reveals how particles 0:10:06.080 --> 0:10:08.880 can interfere with themselves and have the chance to be 0:10:08.920 --> 0:10:11.560 in multiple places at once. We dog into that experiment 0:10:11.559 --> 0:10:14.520 with a fun conversation with Adam Becker, the author of 0:10:14.600 --> 0:10:17.640 What Is Real, and today we're gonna go double down 0:10:17.679 --> 0:10:21.400 on those experiments and think about even crazier versions. Yeah, so, 0:10:21.440 --> 0:10:23.720 what is a quantum erasor now, Daniels this a thing 0:10:23.960 --> 0:10:26.880 or like a concept. Yeah, it's both. It was first 0:10:26.920 --> 0:10:29.319 a concept and then people made it a thing. It's 0:10:29.440 --> 0:10:31.480 like that in quantum mechanics, a lot of people think, well, 0:10:31.559 --> 0:10:34.880 if the universe really is that way, here's a ridiculous 0:10:34.880 --> 0:10:37.600 scenario that should lead to a silly result. And then 0:10:37.679 --> 0:10:40.560 physicists go out and they do the experiment. They make 0:10:40.600 --> 0:10:42.360 it real. They figure out a way to like build 0:10:42.400 --> 0:10:45.720 it in their lab to test that crazy property universe, 0:10:45.880 --> 0:10:48.640 and they get these ridiculous results, which in the end 0:10:48.679 --> 0:10:51.240 you have to accept because that's what the experiment says. 0:10:51.400 --> 0:10:54.559 They say, the universe really works that way. All right, 0:10:54.559 --> 0:10:57.720 Well we'll dig into it, we'll rub that quantum erazor 0:10:58.360 --> 0:11:00.720 all of our brains and see there is anything left 0:11:00.760 --> 0:11:03.360 at the end. But first we were wondering if how 0:11:03.360 --> 0:11:06.000 many people out there had thought about this question or 0:11:06.040 --> 0:11:09.000 even heard the term quantum eraser. So Daniel went out 0:11:09.000 --> 0:11:12.440 there and ask people on the internet what they thought 0:11:12.480 --> 0:11:15.240 a quantum eraser is. That's right. So if you'd like 0:11:15.320 --> 0:11:17.720 to be a participant in our virtual person on the 0:11:17.760 --> 0:11:21.280 street interviews and love to speculate about physics without looking 0:11:21.320 --> 0:11:24.240 anything up, then please write to us two questions at 0:11:24.360 --> 0:11:26.800 Daniel and Jorge dot com. All right, so think about 0:11:26.840 --> 0:11:28.840 it for a second. If a random physicist came up 0:11:28.840 --> 0:11:31.160 to you on the street and you didn't run away first, 0:11:31.200 --> 0:11:33.360 and I actually listened to them, and they asked you, 0:11:33.400 --> 0:11:36.520 what is a quantum eraser? What would you say? You 0:11:36.520 --> 0:11:41.160 are people's answers something an angry physics grad student uses. 0:11:41.920 --> 0:11:45.360 I have no idea. Maybe something that erases things at 0:11:45.440 --> 0:11:48.400 random and like gets rid of things, because that's what 0:11:48.480 --> 0:11:52.679 quantum generally is, is the randomness. Quantum araser could be 0:11:52.760 --> 0:11:57.080 something that we invent in the future to erase quantum 0:11:57.120 --> 0:12:00.959 mechanics and quantum physics just because pretty hard to understand. 0:12:01.000 --> 0:12:02.520 If we don't have it around anymore, we don't have 0:12:02.559 --> 0:12:05.359 to deal with it. We can stick with general relativity 0:12:05.400 --> 0:12:08.240 and regular gravity. So yeah, just get rid of that stuff. Really, 0:12:11.720 --> 0:12:14.160 I don't know either if I were to compare a 0:12:14.240 --> 0:12:17.360 quantum or race or to a regular racer, which essentially 0:12:17.440 --> 0:12:23.439 just kind of distorts the little graphite particles and absorbs 0:12:23.480 --> 0:12:25.560 them in in a way that you know, it gets 0:12:25.640 --> 0:12:29.120 rid of the material on a piece of paper or something, 0:12:29.200 --> 0:12:31.520 so that you know you can reuse that material to 0:12:31.520 --> 0:12:34.200 write on something. Maybe a quantum race, or some sort 0:12:34.200 --> 0:12:38.559 of force or phenomenon that causes sometime of particles to 0:12:38.880 --> 0:12:43.080 break up from a given area or concentration, so that 0:12:43.480 --> 0:12:47.880 the information is very very difficult to understand, or to 0:12:47.960 --> 0:12:50.680 receive or to observe. Maybe well, I'm a teacher, and 0:12:50.760 --> 0:12:53.240 I know that my students use a razors to hide 0:12:53.280 --> 0:12:57.920 their mistakes, So I think a quantum e razor is 0:12:58.000 --> 0:13:02.040 something that quantum physicists used to hide their errors from 0:13:02.040 --> 0:13:05.240 everyone else. All I can come up with for that is, 0:13:06.120 --> 0:13:07.960 sometimes you make a mistake and it's for the better, 0:13:08.160 --> 0:13:10.520 it's a better idea than what you originally planned. And 0:13:10.559 --> 0:13:14.720 sometimes it's a big catastrophe. But since you don't know 0:13:14.760 --> 0:13:18.480 ahead of time, you use your quantum eraser two either 0:13:18.600 --> 0:13:21.480 undo your mistake or make it permanent, and you just 0:13:21.600 --> 0:13:26.280 roll the dice and let fate decide. No idea. Never 0:13:26.320 --> 0:13:29.240 heard of a quantum eracer, but the image of a really, 0:13:29.400 --> 0:13:33.120 really kindy eraser pops into my mind. So let's say 0:13:33.200 --> 0:13:39.640 a tool that allows you to change the sub potomic 0:13:39.679 --> 0:13:45.400 structure of stuff. I would guess that a quantum eracer 0:13:45.760 --> 0:13:51.000 is having to do with erasing particles that have certain 0:13:51.080 --> 0:13:55.320 quantum states. Thereby leaving behind particles that are in the 0:13:55.360 --> 0:13:58.520 state you want, uh that, or it's the weapon that 0:13:58.559 --> 0:14:01.800 they used in the movie Racer with Arnold Schwarzenegger. All right, 0:14:02.040 --> 0:14:04.360 a lot of fun answers here. Everyone's a comedian on 0:14:04.400 --> 0:14:06.880 the internet. Well, especially if I have no idea what 0:14:06.920 --> 0:14:08.880 we're talking about, then they got to go to that 0:14:08.960 --> 0:14:13.960 joking place. I like the joke about the really tiny eraser, right, Yeah, 0:14:14.040 --> 0:14:16.319 like if you have a quantum pencil, I guess it 0:14:16.320 --> 0:14:19.080 would have a quantum eraser on the one end of it. Yeah, 0:14:19.200 --> 0:14:21.960 or e raises quantum particles or something like that. I'm 0:14:22.000 --> 0:14:24.760 imagining a super tiny little vacuum cleaner that like slurps 0:14:24.880 --> 0:14:27.840 up electrons. Yeah, and and those one with them passes 0:14:27.840 --> 0:14:31.160 them through a wormhole into another universe. I guess, tantalizing. 0:14:31.440 --> 0:14:33.440 All right, well, let's get into this concept of a 0:14:33.520 --> 0:14:36.040 quantum erasor Daniel, you're saying it has something to do 0:14:36.120 --> 0:14:38.920 with the double slit experiment. Now, this is going to 0:14:39.000 --> 0:14:41.080 be kind of hard because I feel like this is 0:14:41.120 --> 0:14:43.400 a podcast and it's an audio only and this is 0:14:43.440 --> 0:14:47.040 a very kind of visual experiment. But I guess we 0:14:47.280 --> 0:14:49.240 can try our best to describe what it is. Yeah, 0:14:49.240 --> 0:14:50.840 maybe we can add a dance element to it. Do 0:14:50.880 --> 0:14:52.600 you think that will help? Yeah? Or I could draw 0:14:52.640 --> 0:14:55.800 our tunes. I'm doing watercolor painting at the same time 0:14:55.840 --> 0:14:57.760 as we do our podcast. By the way, Oh really, 0:14:57.800 --> 0:15:01.760 you're in a quantum artistic s am. Know. This quantum 0:15:01.840 --> 0:15:04.680 er racer is an experiment that's like a permutation or 0:15:04.720 --> 0:15:08.080 an add on to the basic double slit experiment. So 0:15:08.120 --> 0:15:11.000 to understand why the quantum racer is so weird and crazy, 0:15:11.080 --> 0:15:13.080 you definitely have to understand what's going on in the 0:15:13.120 --> 0:15:15.440 double slit experiment. And so I think we're gonna have 0:15:15.480 --> 0:15:18.600 to use our words to describe the wiggly crazy nature 0:15:18.640 --> 0:15:20.800 of that experiment, and then we can build on it 0:15:20.880 --> 0:15:22.880 to get to the quantumer racer. All right, So I 0:15:22.920 --> 0:15:26.280 guess the double slicks experiment starts with a single slit first. 0:15:26.320 --> 0:15:28.640 I guess we'll explain that one, and then we'll multiply 0:15:28.680 --> 0:15:31.600 by two. So the basic experiment is like you have 0:15:31.720 --> 0:15:35.040 a wall, like a barrier, like a plate of metal, 0:15:35.160 --> 0:15:36.880 and you cut a little slit on it, like a 0:15:36.880 --> 0:15:40.080 little opening that's long in one direction, and then you 0:15:40.120 --> 0:15:42.520 shoot like a laser or like just a regular beam 0:15:42.520 --> 0:15:44.960 of light through it and then onto a wall behind 0:15:45.040 --> 0:15:48.240 the first wall. Yeah, exactly. So imagine your mind some 0:15:48.280 --> 0:15:50.600 source of light. A laser is good because then you 0:15:50.640 --> 0:15:53.440 have photons of all the same wavelength in the same direction, 0:15:53.800 --> 0:15:55.440 and then a screen on the other side with the 0:15:55.520 --> 0:15:57.840 laser hits. What do you get. You get a laser spot. Now, 0:15:57.880 --> 0:16:01.080 as you say, put something in between, like a barrier 0:16:01.360 --> 0:16:03.640 that has a very thin slit in it. Then what 0:16:03.680 --> 0:16:05.480 do you see on the screen Instead of the full 0:16:05.560 --> 0:16:08.520 laser spot. Now you see like a slice of that spot. 0:16:08.800 --> 0:16:11.040 You get a smooth pattern on the screen, but it's 0:16:11.080 --> 0:16:13.160 sort of cut by the slit in the barrier, and 0:16:13.240 --> 0:16:16.200 it has smooth edges, not a sharp edge, because that's 0:16:16.200 --> 0:16:18.040 what happens when light goes through a slit, intends to 0:16:18.120 --> 0:16:21.040 like spread out a little bit and smooth out. So 0:16:21.120 --> 0:16:23.360 the thing you start with is this single slit where 0:16:23.360 --> 0:16:25.480 the light goes through and hits the barrier on the 0:16:25.520 --> 0:16:28.240 other side, right, and you get a smooth light pattern 0:16:28.320 --> 0:16:30.600 on the other side. Now, the weird thing is in 0:16:30.880 --> 0:16:33.040 what happens if you put a second slit next to 0:16:33.040 --> 0:16:35.280 the first slip, right, that's right, So now you put 0:16:35.320 --> 0:16:38.840 two slits really close together so that the beam could 0:16:38.920 --> 0:16:41.600 pass through one slit or the other slit, and once 0:16:41.640 --> 0:16:43.960 you get on the other side, instead of having like 0:16:44.200 --> 0:16:47.840 two smooth patterns or you know, the simple addition of 0:16:47.960 --> 0:16:50.520 two patterns like you saw before, now you get an 0:16:50.560 --> 0:16:53.760 interference pattern, which means that you get these patterns of 0:16:53.880 --> 0:16:56.120 light and dark and light and dark and light and dark. 0:16:56.360 --> 0:16:59.560 And what's happening there is interference. Just like if you 0:16:59.640 --> 0:17:01.840 have waves when you add them, if one wave is 0:17:01.880 --> 0:17:04.239 going up while the other wave is going down, then 0:17:04.280 --> 0:17:07.000 they cancel each other out. Whereas if one wave is 0:17:07.000 --> 0:17:08.639 going up and the other one is going up at 0:17:08.640 --> 0:17:10.639 the same time, then they add up on top of 0:17:10.680 --> 0:17:13.400 each other. They get twice as strong. So the interference 0:17:13.440 --> 0:17:16.199 pattern has these slices that are twice as bright as 0:17:16.240 --> 0:17:19.000 the previous pattern, and these dark slices as well. And 0:17:19.000 --> 0:17:21.440 that's because you have two sources of light. Now each 0:17:21.480 --> 0:17:23.720 of the slits is giving you photons and they can 0:17:23.760 --> 0:17:28.240 either constructively or destructively interfere on the screen. Right because 0:17:28.280 --> 0:17:30.399 I guess you're shooting a laser at both slits at 0:17:30.400 --> 0:17:32.480 the same time, or you're like shooting a laser and 0:17:32.560 --> 0:17:34.920 it and the beam of the laser kind of goes 0:17:34.960 --> 0:17:36.879 through both slits at the same time, right, Yeah, the 0:17:36.920 --> 0:17:39.639 slits are very narrow and very very close together. This 0:17:39.760 --> 0:17:42.080 only works if the scale we're talking about here is 0:17:42.080 --> 0:17:44.800 sort of related to the wavelength of light that we're 0:17:44.800 --> 0:17:47.480 shooting at it. So this needs to be very microscopic. Right, 0:17:47.480 --> 0:17:49.560 So if you have one slid, you get a fuzzy, 0:17:49.640 --> 0:17:52.359 like a plain fuzzy image on the other side. But 0:17:52.400 --> 0:17:55.520 if you have two slids, then suddenly it's not a smooth, 0:17:55.600 --> 0:17:59.280 fuzzy image. It's like a weird Rippley kind of image, 0:17:59.320 --> 0:18:02.720 which means at somehow light is interacting with itself. Yeah, 0:18:02.760 --> 0:18:04.440 in this case, we don't know if the light is 0:18:04.480 --> 0:18:06.800 interacting with itself. You could say, hey, look, light is 0:18:06.800 --> 0:18:10.080 a wave, and waves interfere. This happens with waves in 0:18:10.119 --> 0:18:12.199 the bathtub, it happens with waves in the air. Like 0:18:12.600 --> 0:18:16.119 noise canceling headphones, right, they generate a second pattern of 0:18:16.240 --> 0:18:19.880 noise to cancel out the noise that's coming into your ear. 0:18:20.280 --> 0:18:23.840 So interference in waves is not necessarily a quantum mechanical thing. 0:18:23.840 --> 0:18:26.040 It's just a wave thing. So in this version of 0:18:26.040 --> 0:18:28.520 the experiment so far, you could just say, look, light's 0:18:28.520 --> 0:18:31.479 a wave. It's interfering, No big whoop. It gets quantum 0:18:31.520 --> 0:18:34.040 when you remember that the beam is actually made not 0:18:34.200 --> 0:18:38.399 of waves but of photons, little individual packets, and so 0:18:38.480 --> 0:18:40.760 you can take it to the next step by slowing 0:18:40.840 --> 0:18:44.000 down the experiment and dimming the laser. So that's shooting 0:18:44.080 --> 0:18:47.120 like one photon through the experiment at a time. Yeah, 0:18:47.160 --> 0:18:49.960 you shoot one photon at a time, and then you 0:18:49.960 --> 0:18:52.159 would think that just throwing like one ft doon at 0:18:52.160 --> 0:18:54.960 a time, this photon would pick like the right or 0:18:55.000 --> 0:18:56.640 the left slid and then end up on the other 0:18:56.640 --> 0:18:58.320 side of the wall and you would get the same 0:18:58.400 --> 0:19:01.359 fuzzy smooth pattern. But the weird part I guess is 0:19:01.359 --> 0:19:03.280 that you're shooting one ft at a time, but you 0:19:03.320 --> 0:19:05.879 still get the ripley kind of interference pattern on the 0:19:05.880 --> 0:19:08.840 other side. Exactly. You expect that if you shoot one 0:19:08.840 --> 0:19:11.119 photon at a time that it can't interfere because you 0:19:11.160 --> 0:19:14.359 were thinking, well, the interference comes from two photons going 0:19:14.400 --> 0:19:16.960 through both slits at the same time. Now you have 0:19:17.080 --> 0:19:20.399 just one photon in the experiment, so what's it interfering with? 0:19:20.440 --> 0:19:23.440 Because you still see the interference pattern on the other 0:19:23.480 --> 0:19:25.360 side of the screen and you shoot one photon through 0:19:25.359 --> 0:19:27.439 at a time. It's just that it takes longer to 0:19:27.480 --> 0:19:29.640 build up if you watch it for an hour or so. 0:19:29.680 --> 0:19:33.000 As those photons go through, one lands here, one lands there, 0:19:33.200 --> 0:19:35.879 one lands this other spot, it gradually builds up that 0:19:36.000 --> 0:19:40.399 interference pattern. So what's it interfering with. It's interfering with itself. 0:19:40.760 --> 0:19:43.439 It has the probability to go through both slits, and 0:19:43.480 --> 0:19:47.000 that wave function, which controls where a quantum particle goes, 0:19:47.440 --> 0:19:51.240 interferes with itself and creates this probability distribution on the 0:19:51.280 --> 0:19:54.960 screen for where it might land, and that probability distribution 0:19:55.280 --> 0:19:58.399 has the interference effects inside of it, and that's why 0:19:58.480 --> 0:20:01.240 you get this interference pattern. Every photon that goes through 0:20:01.600 --> 0:20:04.960